Applications of Vertical Seismic Profiling at NTS

Conference · Tue Sep 01 00:00:00 EDT 1987

OSTI ID:6025727

Burkhard, N R

Vertical Seismic Profiling (VSP) data can be used to refine the geologic interpretation of the structural setting around an emplacement hole at NTS. Recent upgrades to the seismic recording equipment routinely fielded by the NTS logging contractor permit VSP data to be obtained quickly as needed without external support. VSP data can be used in many different ways. Traditionally, VSP data have been used as a tool to assist in the interpretation of surface seismic Common Depth Point (CDP) reflection data. LLNL has been examining several direct applications to the geologic characterization of an emplacement site. VSP data from a single surface seismic source location near an emplacement hole can be used to determine the depth and apparent dip of reflecting horizons below the bottom of the hole. With multiple surface seismic source locations, the true dip of a reflector can be determined. However, geologic interpretation is still required to properly identify the reflector. In some cases, the evidence of the presence or absence of the reflector is all that is required for containment evaluation. An example of this technique (along with its shortcomings) using data from hole, U20ar is presented. Offset VSP data are obtained when the surface source is not near the well head. This technique uses the direct and reflected energy and differs from half-refraction techniques that utilize only the refracted head waves. A convenient method of imaging these data involves the transformation of these data from the traditional VSP domain to a CDP domain. In the CDP domain, the transformed VSP data resemble a CDP reflection section. Standard surface seismic reflection techniques can be utilized to determine the structure on a portion of the plane defined by the emplacement hole and the surface seismic source location. Data from experimental deployments of this technique at hole, U4ag are presented.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6025727
• Report Number(s): UCRL-96347; CONF-870961-5; ON: DE88001886
• Country of Publication: United States
• Language: English

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BOREHOLES
CAVITIES
GEOPHYSICAL SURVEYS
NATIONAL ORGANIZATIONS
NEVADA TEST SITE
REFLECTION
SEISMIC SURVEYS
SURVEYS
US DOE
US ORGANIZATIONS